@snmiller, I rather agree that the greenish cast “doesn’t seem completely out of place”
However, I thought it would be an interesting challenge to see what I could do in GIMP to remove it! I was originally thinking about selecting the background and desaturating it, but it turns out there’s a much easier way to do it!
Open your image in GIMP and go to ” Colors > Curves ”
Now select the “Green” color curve option.
Now grab the line right in the middle and pull it down a bit, you can adjust it till it looks about right.
Voila! Green cast is all gone! Note that it does affect the other colors slightly, but I’m assuming that if the rock was “off” then the rest of the picture was too, so the whole thing should be more realistic. You may want to back down slightly on the saturation, since modifying the green channel basically made the whole leaf more saturated.
UPDATE: I created a tutorial with this same material here.
